Tr. Clark et al., COAL DEPYRITIZATION BY THE THERMOPHILIC ARCHAEON METALLOSPHAERA-SEDULA, Applied and environmental microbiology, 59(8), 1993, pp. 2375-2379
The kinetics of pyrite oxidation by Metallosphaera sedula were investi
gated with mineral pyrite and two coals with moderate (Pittsburgh no.
8) and high (New Brunswick, Canada) pyritic sulfur content. M. sedula
oxidized mineral pyrite at a greater rate than did another thermophile
, Acidianus brierleyi, or a mesophile, Thiobacillus ferrooxidans. Maxi
mum rates of coal depyritization were also greater with M. sedula, alt
hough the magnitude of biological stimulation above abiotic rates was
notably less than with mineral pyrite. Coal depyritization appears to
be limited by the oxidation of pyrite with ferric ions and not by the
rate of biotic oxidation of ferrous iron, as evidenced by the maintena
nce of a high ratio of ferric to ferrous iron in solution by M. sedula
. Significant precipitation of hydronium jarosite at elevated temperat
ure occurred only with New Brunswick coal.